New IMAS research pinpoints Tassal’s Okehampton risk

Posted by Daniel Patman3067pts on July 04, 2017

The findings of a new report by the Institute of Marine and Antarctic Studies (IMAS), released today, raises serious concerns about Tassal’s stocking levels in Macquarie Harbour and the shelf life of their controversial Okehampton Bay development, according to Tasmania’s peak environment group.

“New IMAS research shows that over summer in Macquarie Harbour, fish are crowding into just 2 metres of their 17-metre depth pen. Given Tassal are stocking at double the rate of other salmon companies in the harbour, the IMAS findings raise serious concerns about animal welfare standards on Tassal’s farms,” says Laura Kelly, Environment Tasmania.

The IMAS research was funded by Sense-T, a partnership between the University of Tasmania, CSIRO and the Tasmanian Government, and also funded by the Australian Government. It concluded that it is crucial for the aquaculture industry to determine how climate change will impact on their ability to stock heavily in waters experiencing warming temperatures and falling oxygen levels.

“This research provides further scientific evidence that Tassal’s Okehampton Bay development should not proceed. CSIRO described water temperatures of 23 degrees Celsius on Tasmania’s east coast in 2016 as a window into the state’s future. We know salmon experience sub-lethal stresses in water temperatures over 18 degrees Celsius.”

“Pushing into more warm, inshore areas might be saving Tassal a buck on infrastructure, but their Okehampton Bay investment just doesn’t stack up when you consider warming water temperatures. They must be factoring in serious mortalities, but may have failed to price-in the risk of mass fish kills, and consumer rejection of a product coming from a farm that breaches fish welfare conditions,” Ms Kelly said.

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I have now read the paper and also been in dialogue with the first author. I believe you (ET) are wrongly over-extrapolating the results of Stehfest et al.‘s research in Macquarie Harbour; this is not conducive to your case about Tassal’s activities and their potential effects on the marine environment at Okehampton Bay.

Key inaccuracies in ET’s citation of this research include:

1) “IMAS findings raise serious concerns about animal welfare standards on Tassal’s farms”: Stehfest et al. did not investigate “animal welfare” of the livestock at Macquarie Harbour, and did not draw any firm conclusions about the welfare of fish given the density in the 2m depth band during the period of study.

2) “it is crucial for the aquaculture industry to determine how climate change will impact on their ability to stock heavily in waters experiencing warming temperatures and falling oxygen levels”.

There is currently no fine-scale climate or hydrodynamic study or model for Okehampton Bay that can predict the response of the water column to temperature change or oxygenation levels. It is within the bounds of known data and models that this site could cool and/or become more oxygenated due to increased storm activity as a result of climate change. Moreover, it is very misleading to compare results from Macquarie Harbour, which is a stratified, enclosed estuarine waterbody to Okehampton Bay, which is a semi-open marine, tidal system.

If ET wants to maintain any credibility in this issue, it needs to make sure that its reading and citation of the scientific evidence is accurate and correct – not just “cherry picking” what looks like support for a view already determined in advance.